The efficiency of natural gas turbines is directly linked to the turbine inlet temperature, or the combustor exit temperature. Further increasing the turbine inlet temperature damages the turbine components and limits their durability. Advances in turbine vane cooling schemes protect the turbine components. This thesis studies the conjugate effects of internal cooling, film cooling and thermal barrier coatings (TBC) on turbine vane metal temperatures. Two-dimensional thermal profiles were experimentally measured downstream of a single row of film cooling holes on both an adiabatic and a matched Biot number model turbine vane. The measurements were taken as a comparison to computational simulations of the same model and flow conditions. To improve computational models of the evolution of a film cooling jet as it propagates downstream, the thermal field above the vane, not just the footprint on the vane surface must be analyzed. This study expands these data to include 2-D thermal fields above the vane at 0, 5 and 10 hole diameters downstream of the film cooling holes. In each case the computational jets remained colder than the experimental jets because they did not disperse into the mainstream as quickly. Finally, in comparing results above adiabatic and matched Biot number models, these thermal field measurements allow for an accurate analysis of whether or not the adiabatic wall temperature was a reasonable estimate of the driving temperature for heat transfer. In some cases the adiabatic wall temperature did give a good indication of the driving temperature for heat transfer while in other cases it did not. Previous tests simulating the effects of TBC on an internally and film cooled model turbine vane showed that the insulating effects of TBC dominate over variations in film cooling geometry and blowing ratio. In this study overall and external effectiveness were measured using a matched Biot number model vane simulating a TBC of thickness 0.6d, where d is the film cooing hole diameter. This new model was a 35% reduction in thermal resistance from previous tests. Overall effectiveness measurements were taken for an internal cooling only configuration, as well as for three rows of showerhead holes with a single row of holes on the pressure side of the vane. This pressure side row of holes was tested both as round holes and as round holes embedded in a realistic trench with a depth of 0.6 hole diameters. Even in the case of this thinner TBC, the insulating effects dominate over film cooling. In addition, using measurements of the convective heat transfer coefficient above the vane surface, and the thermal conductivities of the vane wall and simulated TBC material, a prediction technique of the overall effectiveness with TBC was evaluated. / text

Using a comparative spatial and temporal analysis on sediment cores from 8 lakes in the Mackenzie River Delta uplands region, NT, Canada, this study assessed how persistent organic pollutant (POP) deposition to lake sediments was affected by: (1) the presence of retrogressive thaw slumps on lake shores; and (2) changes occurring with increased autochthonous primary productivity. POPs examined included polychlorinated biphenyls (PCBs), penta- and hexachlorobenzenes (CBzs), and dichlorodiphenyltrichloroethane and metabolites (DDTs). Surface sediments of slump-affected lakes contained higher total organic carbon (TOC)-normalized POP concentrations than nearby reference lakes unaffected by thaw slumps. Inorganic sedimentation rates were positively related to contaminant concentrations, suggesting that the influx of siliciclastic material reducing organic carbon in slump-affected lake water indirectly results in higher concentrations of POPs on sedimentary organic matter. This explanation was corroborated by an inverse relationship between sedimentary POP concentrations and TOC content of the lake water. Deposition proxies of autochthonous carbon were not significantly correlated to POP fluxes of surface sediments, and historical profile fluctuations did not coincide with variation in POP deposition. Thus this study does not support the contention that algal-derived organic carbon increases the delivery of organic pollutants to sediments (the algal-scavenging hypothesis), as previously proposed for mercury. Higher POP concentrations observed in surface sediments of slump-affected lakes are best explained by simple solvent switching processes of hydrophobic contaminants onto a lower pool of available organic carbon when compared to neighbouring lakes unaffected by thaw slump development.

Using a comparative spatial and temporal analysis on sediment cores from 8 lakes in the Mackenzie River Delta uplands region, NT, Canada, this study assessed how persistent organic pollutant (POP) deposition to lake sediments was affected by: (1) the presence of retrogressive thaw slumps on lake shores; and (2) changes occurring with increased autochthonous primary productivity. POPs examined included polychlorinated biphenyls (PCBs), penta- and hexachlorobenzenes (CBzs), and dichlorodiphenyltrichloroethane and metabolites (DDTs). Surface sediments of slump-affected lakes contained higher total organic carbon (TOC)-normalized POP concentrations than nearby reference lakes unaffected by thaw slumps. Inorganic sedimentation rates were positively related to contaminant concentrations, suggesting that the influx of siliciclastic material reducing organic carbon in slump-affected lake water indirectly results in higher concentrations of POPs on sedimentary organic matter. This explanation was corroborated by an inverse relationship between sedimentary POP concentrations and TOC content of the lake water. Deposition proxies of autochthonous carbon were not significantly correlated to POP fluxes of surface sediments, and historical profile fluctuations did not coincide with variation in POP deposition. Thus this study does not support the contention that algal-derived organic carbon increases the delivery of organic pollutants to sediments (the algal-scavenging hypothesis), as previously proposed for mercury. Higher POP concentrations observed in surface sediments of slump-affected lakes are best explained by simple solvent switching processes of hydrophobic contaminants onto a lower pool of available organic carbon when compared to neighbouring lakes unaffected by thaw slump development.